We are proposing to study 2000 participants in a randomized trial of 240 mg of ginkgo biloba as compared to placebo in men and women, median age of 80. Approximately 1500 participants will be recruited from current Cardiovascular Health Study (CHS) participants who had a clinic visit in 1998-99 and 500 will be recruited from the community. There are four clinical centers: Pittsburgh, Hagerstown, Winston-Salem and Sacramento, California, and a Coordinating Center at the University of Washington, Seattle. Following randomization, participants will be seen at 1 month, 4 months, 8 months and every four months thereafter during the trial for evaluation of adherence, and side effects. There will be a telephone call at every 6 months to determine morbidity and change in cognition (telephone interview for cognition (TICS), and annual examination that will include repeat of 3MSE, DSST, and 10 battery neuropsychological evaluation and informant interview. ApoE has already been measured for all CHS participants. The primary endpoint is dementia, secondary endpoint will be Alzheimer's Disease, vascular dementia, and other endpoints include incidence of vascular disease, changes in cognitive function scores over time, and changes in functional status. We are proposing a six year study. We estimate incidence of dementia at about 3.5 percent/year over six years and a total mortality of 6 percent/year. We would have about 90 percent power alpha.05 to determine a 35 percent reduction, and 80 percent power for 30 percent reduction in incidence of dementia. We estimate approximately 250 dementia cases in the study based on 3.5 percent yearly incidence. The diagnosis of dementia will be based on neuropsychological testing, neuro exam, MRI functional measurements, and review by a central adjudication committee and classified by DSM IV, NINCDS criteria and ADRTC criteria for vascular disease.